The effect of oxidized starches on chalcopyrite flotation

• Published in: Minerals engineering 2021-05, Vol.165, p.106749, Article 106749
• Main Authors: Chimonyo, Wonder, Fletcher, Brenton, Peng, Yongjun
• Format: Article
• Language: English
• Subjects: Adsorption; Carbonyl group; Carboxyl group; Depression; Flotation; Oxidised starch
• ISSN: 0892-6875; 1872-9444
• DOI: 10.1016/j.mineng.2020.106749

•Starch oxidation results in specific molecular size and structural transitions.•High Ox 1/120 adsorption occurred on chalcopyrite surface with a largely dense morphology.•Ox 5/120 structures revealed restricted adsorption and adopted a patchy morphology.•Ox 10/120 adsorbed continually and illustrated spluttered numerous small domains.•Variations of oxidized starch structure features affect chalcopyrite flotation. In our previous study, a NaClO oxidized wheat starch (Ox 5/120) showed promising selectivity between chalcopyrite and graphite flotation compared to the native counterpart. Building from that, this paper presents a systematic investigation conducted on a series of NaClO oxidized starches in a quest to minimize chalcopyrite depression during flotation. Active chlorine of different concentrations was used in the synthesis of the starch derivatives (Ox 1/120, Ox 5/120 and Ox 10/120). Each chlorine level varies the degree of starch oxidation with respect to depolymerisation leading to new orders of molecular weight and size distributions of the polymer fractions. This is in conjunction with the proportion and type of carbonyl functional groups generated. A combination of adsorption isotherms and nanoscale characterisation using AFM revealed dissimilar adsorbability and visual morphological features, providing new insights into the depressive actions of oxidized starches during chalcopyrite flotation.